Degating device for plastic molds



Oct. 9, 1951 1 w. vlNAL DEGATING DEVICE FOR PLASTIC MoLDs 2 Sheets-Sheet l Filed-Julyv 8, 194s k 2 le.

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Patented ct. 9, 19V-51 7 1 DEGA'IING. DEVICE Fon PLASTIC Mo'LDs Leroy W. Vnal, Leominster, Mass., assignor to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of. Delaware Application July 8, 1948,'Serial No. 37,722

This invention relates to improvements in degating devices contained wholly Within the mold itself and operable upon opening the mo1d to separate the gate or sprue from the molded article so that the latter is removed in complete salable condition with no further operation necessary.

The principal object of the invention resides` in the provision of a degating ,device as above stated which is simple in construction and positive in operation; the provision of a degating device automatically operable upon slight opening of the mold after the molding operation so that the sprue and article may be ejected separately bythe Vusual ejector pins without interference therewith; and the provision of relatively moving mold cavity parts and a stripper blade or punch located at the sprue to strip or punch the latter cleanly from the molded articlev just as the mold opens in the usual molding cycle.

Another object of the invention resides in the provision of a molding cavity part having a spring to thrust the same out of the platen as the mold opens, and a sprue stripper or punch on the opposite platen of the mold also having a spring to thrust the same out, but in the opposite direction, the stripper or punch not interfering in any way with the spring pressed molding part and merely separating the sprue from the molded article at the initiation of the opening cycle -of the molding machine.

My invention further relates to arrangements and combinations of parts which will be hereinafter described yand more particularly pointed out in the appended claims.

Reference is to be had to the accompanying drawings, in which:

Fig. 1 is a diagrammatic representation of a mold according to the invention;

Fig. 2 is a view taken on line 2-2 of Fig. l, and showing the location of the sprue in the mold;

Fig. 3 is an enlarged section on line 3-3 of Fig. 1, showing a spring in compressed condition, with the mold closed;

Fig. 4 is a view similar to Fig. 3 but showing the spring with the mold open;

Fig. 5 is an enlarged section on line 5-5 of Fig. 1, and showing the parts, molded article, etc., as they appear after molding but prior to the opening of the mold; and

Fig. 6 is a view similar to Fig. 5 but showing the sprue stripping action as the initial opening of the mold takes place.

In Fig. 1 of the drawings, the plate adjacent 4 Claims. (c1. 11s-.42)

the injection nozle vof the molding machine Vis yindicated at I 8 and this plate 'is providedrwith a bushing I2 to receive the nozzle and formingV the sprue, indicated at I4. There are usually a plurality of plates making up a mold, but herein it is necessary merely to show four plates-one of which has been described. k

The next plate is a molding plate indicated atV I6, this plate :being fixed to plate I0 and contain-4v ing a cavity part I8 floating therein on springs 28 Iarranged on studs 22 threaded into the iloating part I8 and provided with heads 24 limiting the travel of part I8 relative to plate I8 by contact with the bottoms of holes 26 in plate I0 accommodating the stud heads.

For purposes of illustrating the invention, a comb mold is disclosed, in a single place mold; however, any article may be made according to the invention, in molds of any desired number of places. The comb cavity in part I8 is shown at 28 and the parting line is at 38, Figs. 1 and 5. The gate is illustrated at 32, at the inside edge of a tooth 34 of the comb.

The other side of the mold comprises plate 36 to which is Vsecured molding plate 38, the latter having a iixed molding part 40 provided with a cavity A42 complementary to cavity 28 and com-` pleting the same.

Plate 3'8 also contains a block 44 iloating therein by spring means 46 similar to those at 20 and as detailed in Figs. 3 and 4. Thus as mold part I-8 tends to be pressed toward plate 38, block 44 tends to be pressed toward plate I6. Block 44 is the stripping block and fixed therein is a stripper blade or punch `48 held in a slot in block 44 by pins 50.

Blade or punch 48 extends over and beyond gate 32 and actually, in this case, forms a part of the mold defining the sprue. The blade or punch 48 lies in a closely engaging slot in molding part 40, this slot being indicated at 52 in Fig. 6. Upon relative movement of the molded article and the block 44 and blade or punch 48. the operating edge of the latter enters a like and aligned slot 54 in part I8, see Fig. 6. Block 55 is rigidly mounted on plate I0 land with blade I48a pinned to it forms the runner 56 and gate 32. Blade 48a moves in slot 54 and remains in contact with blade 48 until the position shown in Fig. 6 is reached. Looking at Fig. 2. the blade or punch 48 overlies gate 32 and is greater edgewise than the sprue to insure complete removal of the latter.

As the plates start to open after molding. springs 20 urge molding part I8 outwards. to fol` shown in Fig. 6. As plate 36 retreats still further.,

the mold opens completely and the usual eject- 4 plate outwardly of its molding plate, a fixed complementary cavity plate in the other molding plate, a floating stripper block in the latter plate, resilient means tending to thrust the stripper block outwardly thereof in a direction opposite to the yfloating cavity plate, the respective molding plates acting to thrust the floating plate and blockback inwardly vas thevmo'ldcloses, a sprue cavity, andra stripper, bladelori the. block in positionto strip the sprue from the article being molded, as the mold opens.

ing pins come into operation, as usual','to eject the sprue and molded article.,

Having thus described my invention: andV the advantages thereof, I do not wish to ber limited?vr f to the details herein disclosed, otherwise than as..

set forth in the claims, but what'I claimv is z" 1. A mold comprising two main plates adaptedv to be opened and closed for the molding cycle, a flloatrngv cavity plate on one of the main plates, a: relatively Xed Vcomplementary cavity plate` on them-otherkniainplate, a floating stripper block on the latter plate, and `means for the floating plate andb lock to thrust the same outwardly of their respective main plates asv the latter open, thereby achieving a relative motion ofthe stripper block past the molded article, a sprue'cavity, andv a sprue stripping blader on the block, said blade ,overlying the sprue cavity.

2. A degating molclcomprising a pair of main plates for advance and retraction. during the molding cycle, a molding plate on each main plate, a floating cavity plate in one moldingplate, resilient means tending to thrust the floating vcavity 3g` Themold. of claim 2 wherein the stripper blade overlies the sprue and forms a wall of the sprue cavity when themold is closed.

4'. "Il'iem'ldjoiji claim 2 including means limit-f ing the motion of the floating' plate and block.v LEROY W. VINAL.

REFERENCES CITED The following references are of record in the iile of: thisv patent:

UNITED STATES PATENTS France` Jan. 29, 1942v 

